[Catalyst] Suggested minor fixes for Catalyst error output

[Sebastian Riedel]

Ok, discussion closed, we have a solution.

We'll use corner png's served by Static::Simple (just like the  
welcome screen images).
It will fall back to square corners if images are not available  
(deactivated Static::Simple plugin, crash...).

Luke would implement this on monday, patches welcome if you want it  
earlier. :)


--
sebastian